1. Field of the Invention
The present invention relates to a novel cellulase, and a method for producing the same as well as use thereof as an aid for detergents or as a paper treating agent.
2. Description of Prior Art
Development of cellulases has been carried out with view to efficient utilization of biomass resources, particularly cellulose resources. However, utilization of cellulases for biomass on an industrial scale has prevailed not so widely.
On the other hand, as a novel industrial application of cellulase, it has been known that cellulase is effective for increasing the washing power of detergents. For example, it has been confirmed that cellulase is effective for washing denim due to its ability of removing fine fiber dusts (cf. British Patent Nos. 2094826 and 2095275). There have been published many publications on the utilization of cellulase in various steps of paper making such as deinking of waste-paper, bleaching of pulp, and improvement of production processes for regenerated paper and much attention has been directed to cellulase (cf. Japanese Patent Publication Laid-Open Nos. 9299/1984, 80683/1990, European patent Publications Nos. 395792 and 383999, and Tappi Journal vol. 72, No. 6, 197-201 (1989) and vol. 73, No. 12, 197-202 (1990)).
However, under ordinary washing conditions pH of washing liquor is on a higher alkalinity side, and a part of paper making steps is carried out under highly alkaline conditions, resulting in that cellulases used in washing or paper making processes must be alkaline cellulases which can function under highly alkaline conditions. Furthermore, the cellulases must be those which can function stably in the presence of detergents or anionic surfactants used in a part of paper making steps.
Alkaline cellulases produced by microorganisms include those produced by a method in which an alkalophilic bacterium belonging to the genus Bacillus is cultivated and an alkaline cellulase produced is collected (cf. U.S. Pat. No. 3,844,890), a method in which an alkalophilic bacterium belonging to the genus Cellulomonas is cultivated to produce alkaline cellulase 301-A (cf. Japanese Patent Publication Laid-Open No. 224686/1983), and a method in which an alkalophilic bacterium belonging to the genus Bacillus KSM-635 is cultivated to produce alkaline cellulase K (cf. U.S. Pat. No. 4,945,053), respectively. However, these known cellulases are not always stable enough against an anionic surfactant which is one component of detergent. Therefore, there has been a keen demand for development of cellulases which are more stable than ever against anionic surfactants.